The PG staff and PL's are here to listen to the player base, and bring the concerns and issues to the DM team. If needed or requested, we can do so in a discreet or anynomous way if for some reason a player only feels comfortable in that way.
As well, if you feel you need to vent about a particular issue, I am sure there are a number of us willing to listen. Personally, I'd rather have a player vent a bit of frustration privately my way instead of getting onto the forums and leaving the trails of that frustration through five or six different threads.
That being said. . .
Along with Coaan's point about posting complaints on DM decisions…
It is also inappropriate to use another thread or discussion (whose purpose isn't to question that decision) to insult, disparage, or question the ruling or act of a DM in game, whether it is done overtly or discreetly.
